For example, Japanese Laid-Open Patent Publication No. 5-243057 discloses a conventional multilayered device (a thin transformer) which is configured by laminating insulation sheets with conductor coils. In such conventional multilayered device, as shown in FIG. 14, conductors 200 which are formed of a material such as copper foil of a flexible printed circuit board to have coil shapes on a first face (front face) of a flexible insulation sheet 100 of foldable such as the flexible printed circuit board, for example. By laminating such insulation sheet 100, a multilayered device having a desired inductance value can be obtained.
FIG. 15A and FIG. 15B are figures respectively showing a first face (a front face) and a second face (a rear face) of adjoining two folded areas of the insulation sheet 100. In this example, the conductors 200 are formed as coil shape only on the first face (front face) 100A in FIG. 14, and no conductor is formed on the second face (rear face) 100B. As shown in FIG. 15A, the first coil 201 formed on a first foldable area 101 is electrically conducted to a second coil formed on a second foldable area 102. Under a condition that the insulation sheet 1 (SIC: 100) is folded so that the second faces (rear faces) of respective foldable areas are contacted, the first coil 201 of the first foldable area 101 and the second coil 202 of the second foldable area 102 are disposed in parallel with each other via the insulation sheet 100, so that an inductor is formed.